1. Field of the Invention
The present invention relates to a computer program product, system, and method for allocating network bandwidth to prefetch requests to prefetch data from a remote storage to cache in a local storage.
2. Description of the Related Art
Enterprises operating at geographically dispersed sites may utilize an infrastructure for moving, storing and accessing large amounts of data across geographically distributed sites. The International Business Machines Corporation (“IBM”) General Parallel File System (“GPFS”) allows for the caching of data stored in a remote storage at a local storage cache site for use by applications at the local site. GPFS provides tools for management and administration of the GPFS cluster and allows for shared access to file systems from remote GPFS clusters. Panache is a scalable, high-performance, file system caching layer integrated with the GPFS cluster file system that provides a persistent data store at the local cache site which masks wide area network (“WAN”) latencies and outages by using GPFS to cache massive data sets, allowing data access and modifications even when the remote storage cluster is unavailable.
In the Panache system, a home site is a source of original data and a cache site caches data locally in a persistent store for local client applications. When a client application accesses any file, for a first access, the file is fetched from the home site and copied to the GPFS file system at the cache site. Subsequent requests for the file are served from the local cache site eliminating the need of WAN bandwidth. The Panache system maintains data synchronization and consistency between the cache site and the home site copy.
If a client application file access request at the local site results in a cache miss, the reading of the file data from the home-site over WAN can result in significant latency for the applications accessing data. To reduce latency, Panache provides a partial file caching feature, which allows the prefetching of a file on demand basis. If the application has requested a file percentage that exceeds a prefetch threshold, a background prefetch operation may be triggered on the file to copy the file from the home site to the cache site to make available for future application access without network latency.